‘… an adult (aged 16 or over) has full legal capacity to make decisions for themselves (the right to autonomy) unless it can be shown that they lack capacity to make a decision for themselves at the time the decision needs to be made’ (Mental Capacity Act, 2005 [England and Wales]). The legal situation varies slightly between the UK Devolved Authorities, but all specify the tests to be met to define mental incapacity and which individuals or bodies may be appointed as the incapacitated patient’s best interests decision maker. No one can give consent on behalf of a patient with mental capacity.
In the case of critically ill patients with temporary incapacity, for example altered consciousness after trauma, clinicians must give life-saving treatment, including blood transfusion, unless there is clear evidence of prior refusal such as an Advance Decision Document. The patient record should document the indication for transfusion and the patient should be informed of the transfusion when mental capacity is regained (and their future wishes should be respected).
Where the parents or legal guardians of a child under 16 refuse blood transfusion (or other medical intervention) that, in the opinion of the treating clinician, is life-saving or essential for the well-being of the child, a Specific Issue Order (or national equivalent) can be rapidly obtained from a court. All hospitals should have policies that describe how to do this, without delay, 24 hours a day.